In the electronics filed, development of insulating materials having low dielectric constants is advancing. For example, a polyarylene resin has been proposed as an insulating material suitable for an interlayer insulating film for semiconductor devices, a gate insulating film for thin-film transistors (TFT), a stress relaxation layer for a redistribution layer, etc. (Patent Document 1).
Further, a negative photosensitive resin composition has been proposed wherein a polyarylene resin has been provided with photosensitivity (Patent Document 2). With such photosensitivity, microfabrication by photolithography becomes possible in the same manner as e.g. a photoresist. For example, when an interlayer insulating film is formed by using a polyarylene resin having photosensitivity, there is such a merit that a contact hole can easily be formed in the interlayer insulating film by photolithography without using a photoresist.
In recent years, various flexible devices attract attention. For example, for a TFT for a flexible display, an inexpensive resin substrate such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) is preferably used. However, as such a resin substrate has a heat resistant temperature of so low as from 150 to 200° C., it is necessary to produce the TFT at low temperature so that the substrate is maintained to the heat resistant temperature or below in the entire process.
Further, depending on the application, the surface of a cured film with a low dielectric constant is required to have liquid repellency in some cases. For example, in a case where a gate insulating film is formed by a low dielectric constant material and an organic semiconductor layer is provided thereon, in order to increase the degree of orientation of molecules of the organic semiconductor to improve the electron mobility, the surface of the gate insulating film preferably has liquid repellency.
The following Patent Document 3 discloses to add, as an ink repellent, a copolymer having units having a fluorine-substituted alkyl group and units having an ethylenic double bond to a negative photosensitive composition containing a (meth)acrylic resin as the main component.
Further, the following Patent Document 4 discloses that in a method of forming a low dielectric constant insulating film or the like by using a curable composition containing a fluorinated polyarylene prepolymer by means of a heating step at 300° C. or above, by incorporating a compound having a molecular weight of from 140 to 5,000, having a crosslinkable functional group and having no fluorine atoms in the curable composition, the flatness of the film surface is improved.